For over two centuries, opponents of evolution have searched for examples of natural complexity that could have only been created by design. Reverend William Paley was fond of the eye, with its lens, retina, and other components all beautifully fine-tuned to work with one another. These days, the Intelligent Design camp tries to invoke blood clotting cascades or the flagella that bacteria use to move around in the same way. (See here for some refutations of these arguments.) Ironically, one of the most successful, intricate examples of complexity in nature is something creationists never mention: a tumor.

Cancer cells grow at astonishing speeds, defying the many safeguards that are supposed to keep cells obedient to the needs of the body.